Process of and apparatus for the heat curing of materials



Nov. 2, 1943.

PROCESS OF AND APPARATUS FOR THE HEAT CURING OF MATERIALS T T c. E.BENNETT 2,333,143

Filed May 3l, 1940 2 Sheets-Sheet l INVENTOR '4 ATTORNEYS.

Nov. 2,` 1943. Y Q E, BENNETT 2,333,143

PROCESS OF AND APPARATUS FOR` THB HEAT CURING OF MATERIALS Filed May 5l,1940 2 Sheets-Sheet 2 nNvENTR M. mi

AT1-ORN YS i UNITED' STATE Patented Nov. 2, 1943i,`

2,333,143 PATENT ori-'ice PROCESS OF AND APPARATUS FOR THE HEATCURING OFMATERIALS Charles E.

Bennett, Ridgewood, N. J., assignor to The Okonite Company, poration ofNew Jersey Application May 31, 1940, seria1N0.337,975

, 51Claims.

Thisapplication is directed to the heat curing `of materials such asvulcanizable materials, plastics and other heat curable materials.

More specically my invention provides for the cure to be eiectedelectrically and with thematerial being treated either confined or underpressure.

Still more specifically my invention is directed to performing the spion`of a process such as above brieiiy outlined my invention is `theprovicuring operation While moving the material through a mass theweight'of which .or while the material is enclosed in a metal sheathhigh frequency cirpressure applying material is ema liquid, a comminutedto distinguish from an applied which `the curing operation .iscontinuous and takes place while the` material is advancing.` By reasonof the fact that when pressure is employed the same is a static pressurestuffing boxes and the like A further object of my the necessity iseliminated.

invention is the provi- `sion of a process for the heat curing ofmaterials wherein the material being tween `two electrodes connected toa source treated is moved behigh-,frequency electric current, thedielectric i losses in the material being treated causing the desiredheating ofthe same. 4Il! desired one the electrodes mentioned may whichsupplies the static pressure. A still further object ofthe provision ofa procs such as above the heat curing of is cured while in motion, ingbeyond the influence of invention is `the outlined for materials whereinthe material and wherein after passthe electrostatic field.

be the material the cured material is subjected to a cooling `operation.Cooling may be eflected temperature of the by lowering the pressureapplying medium,

or by moving the material through a coolant before it discharges fromthe apparatus.

A still further and more invention is to pass trostatic fieldwhile thematerial is submerged specic object of my the material through an elecastatic-pressure applying medium which is disposed in a.` U `pressureapplying medium may be a liquid semi-liquid and yet stumng boxes orunnecessary.

Other objects of the out hereinafter. Y

In the accompanying trated in sectional elevation two embodiments theinvention:

Fig. 1 shows in sectional elevation;

-tube arrangement, whereby the 4valves are invention will be broughtdrawings I have illusone embodiment of the invention as limiting theinvention to i to any heatcurable or that is a poor electricalconductor. 2 designates a continuous lchamber upwardly `which too may beof metal or other suitable material. In the illustration the tube l0 isto be partment or chamber` l2 provide,

Passaic, N. J., ar cor- (cl. 1ra-s) Fig. 2 is anelevational vieweofanother embodiment; and

Fig. 3 is a section on the line 2--2 of Fig. 2.

For purposes of clarity Il have chosen to illustrate the invention asapplied to the vulcanizing of Athe'insulation of metal conductorsinsulated with rubber and rubber-lke materials. It is to be distinctlyunderstood, however, that this showing is merely illustrative and not tobe construed this art. My invention, as abover pointed out, isapplicable broadly heat settable material Referring to Fig. 1: metalconductor which is fed continuously through spewing apparatus 4 wherethe heat curable insulation 6 is applied. This may be a vuli canizablerubber or other compound. inasmuch as this equipment is old and wellknown I have made no attempt to illustrate it in detail. Theconductorafter receiving its insulation is passed 'over idler roller 8and from thence downwardly through a vertically extending tube IU. Thistube, as illustrated. isof metal but under certain conditions, to behereinafter referred to, this tube need not be electrically conducting.From the bottomof the tube l0 the insulated conductor passes into andthrough a chamber l2 about the lower side of an idler roller I4 and outof the through a vertical tube I6,

employed as an electrode.

The tubes I0 and i6 together with the comin effect, a U- tube containinga static-pressure applying mass 20. "This mass, as above noted, may beliquid, semi-liquid or comminuted. Examples of usable materials arewater, brine, mercury, mixtures of water or other liquid with comminutedsolids, lead oxide, soapstone, etc'. By the use of a U-shapedarrangement such as illustrated I'am not only able to avail myself ofstatic pressure but I may employ a liquid as the pressure medium withoutusing valvesv or stuing boxes. This is of material advantage in that itreduces the equipment necessary for the practice of my invention to avery simple form and injury to the material being treated is avoided.

It will be understood, of course, that the heavv ierthe pressure mediumemployed the shorter the U-tube legs necessary to give the desiredstatic pressure.

Curing of the insulation 6 is effected as it passes through theapparatus by subjecting the insulation tothe action of an electrostaticfield generated, for example, by connecting the conductor 2 and one ofthe metal legsof the U-tube to a source of high frequency current, asindicated at 22 and 24. The current employed is of very high frequency,of the order of several million cycles.

example, an insulatedy conductoris passed through a steamchest, andwherein necessarily' the heat ofthe steam must be 'conducted throughthev material radially, which is not conducive to a. uniform cure, andlimits the thickness of the insulating wall which can be properly cured.

These disadvantages of course are avoided in my process.

It will be appreciated that by passing the material through a U-tube orsimilar arrangement, as Ihave illustrated, the material is subjected toa static pressure during the vulcanizing operation which preventsswelling of the insulation andthe production of a spongy mass.

As above mentioned, the pressure medium 20 may bevconducting, a saltbrine or mercury, for instance. In that event the tubes l and I6 neednot be electricallyconducting and the pressure medium may be employed asone electrode instead.

It may be desirable under some conditions artificially to cool thematerial being ktreated after the curing operation. This may be done inseveral ways.l For example, cooling coils may vbe provided in thecompartment l2.l 'On the other hand, I may use the equipmentillustrated. A body of coolant 26, water for example, may be maintainedon the surface of the material and circulated by pump 28 through coolingcoils 3U.

In the embodiment of the invention as illustrated in Figs. 2 and 3, Ihave shown the curing of the rubber insulation of a conductor. theinsulation being applied, sheathed in metal, vulcanized and the metalsheath removed in a continuous operation.

Referring to this embodiment of my invention,

the metal conductor is continuously taken fromI a supply reel 32. As theconductor is yadvanced rubber insulation 6 is applied thereto andenclosed in a thin metal sheath 34. This is commercial practice, and forthis reason no details of the apparatus for applying the insulation andsheath have been illustrated.

24 designates a conductor leading froma source of high frequency currentof very high frequency of the order of several million. An electrode 25is connected to this conductor and has sliding contact with theadvancing bare conductor 2. The conductor for the other side of thecircuit is designated 22 and it is connected witir` an electrode 23having sliding contactA with the advancing metal sheath 34. 'I'hecontacts 2,3 and 25 are so spaced that they are located at the asdistinguished from those processes Where, for

insulation 6 as the same passes through the electrostatic field causingthe temperature of the lnsulation to rise uniformly to whatevervulcanizing temperature may be desired.

' As above pointed out my invention has been described in connectionwith the curing of the insulation of aniri'siila'ted conductor forpurposes of illustration and clarity of description only. My inventionis applicable to the curing of any heat curable or settable materialwhich is a poor electrical conductor. For brevity and clarity thesematerials in the claims will be referred to as heat curable materials,which expression is to be interpreted to embrace vulcanizable materialsas -well as materials which are not vulcanizable but set under theapplication of heat, such as plastics.

It is to beunderstood that the equipment or apparatus hereinabovedescribed is purely illustrative and thatchanges may be made thereinwithout departing from the spirit vand scope of my invention.

What I claim is: Y

l. The process of thermally curing materials which are poor electricalconductors, which process comprises continuously 'advancing the materialthrough a, conducting liquid which is under hydrostatic pressure Whilepassing the material between two electrodes connected to a source ofhigh frequency alternating current, the conducting liquid constitutingone electrode.

2. Apparatus for the'heat curing of materials, comprising in combinationa U-tube open at both ends for the passage therethrough of the vmaterialto be treated, a liquid or semi-liquid material partially filling theU-tube, guide means in the bottom of the tube for ymaintaining thematerial being treated submerged, whereby the material is subjected tohydrostatic pressure as it is advanced through the tube, and means forcreating ,an electric field of high frequency through" which thematerial passes as it moves through the said tube. y

3. Apparatus for the heat curing of the insulation of electricconductors, said apparatus comprising in combination a U-tube open atits ends rfor the passage of the insulated conductor there- Y through,said U-tube being electrically conducting, a liquid partially fillingthe tube and through which the insulated conductor must pass as ittraverses the tube whereby hydrostatic pressure is applied to theinsulation, and a source of high frequency electricity connected to saidtube and the said conductor, whereby the insulation is subjected to theheating action of a high frequency electrostatic eld as it passesthrough the tube.

4. The process of thermally curing materials n of highelectricresistance, which process comnodal points of the wave employed.In this wayl I obtain the maximumin uniform heating of the insulation 6.

It will be appreciated that the heating eiect is obtained in the sameway as in the embodiment -illustrated in Fig. "1, the dielectric lossesin the y prises advancing the material simultaneously v through anelectrostatic eld and a uid medium which is under hydrostatic pressureto cure the insulation while preventing its distortion, and continuouslycooling the cured material as it continuously passes out of the pressuremedium.

5. The processor curing in situ the insulation of an electric conductor,said process comprising advancing the insulated conductor through-acon.- ducting liquid which is under hydrostatic pressure andsimultaneously subjecting the insulation to the curing action of anelectrostatic field by connecting the conductor and the conductingliquid to a source of high frequency alternating current.

CHARLES E. BENNEIT.

